Figure 7
From: Melatonin the "light of night" in human biology and adolescent idiopathic scoliosis

Effects of exogenous melatonin on nucleus suprachiasmatic neuronal activity (SCN). Melatonin administered during the early night period may resynchronize SCN neurons and thereby reinforce amplitude of SCN output signal without an effect on circadian phase-MT1 receptors. (Modified from [89]).